Electric discharge tube



Sept. 16, 1952 E. T. CASELLINI ELECTRIC DISCHARGE TUBE Filed June 29, 1948 HOURS LIFE i? 4 l'zz'o Mamas Case l/l'ill' IN V EN TOR.

ATTORNEY Patented Sept. 16, 1952 ELECTRIC DISCHARGE TUBE 'Ezio Thomas Casellini, Salem, Mass, assignor to Sylvania Electric Products Inc., Salem, Mass., a corporation of Massachusetts Application June29, 1948, Serial No. 35,905

This invention relates to electric resonator and discharge tubes containing ionization quenching gases such as water vapor and the like.

The water vapor or other quenching gas has a tendency to clean up orgradually disappear, causing a change in the characteristics of the device. For example, in the case of the automatic transmit-receive switchtube commonly used in radar equipment, the ,so-called recovery time will rise sharply as the water vapor content drops below a particular value.

My invention'prevents this clean up, and in the case of such tubes, greatly increases the life for which the'tubes can be operated without excessive increase in recovery time.

I achieved this result by placing in the tube a compound such as sodium hydroxide, which apparently reacts with any carbon-containing gases in the tube to remove them by forming a sodium carbonate or the like and releasing. water. The carbon or organic material should be removed from the tube parts as much as possible at the outset for example, by firing them in wet hydrogen during manufacture. But some carbon will remain, and the addition of a compound such as I have mentioned is necessary to produce a long lived tube.

Other features, objects and advantages of the invention will be apparent from the following specification in which:

Fig. 1 shows a perspective view of a device embodying the invention.

Fig. 2 is a cross-section along the line 2-2 in Figure 1 through a resonator in the device;

Fig. 3 shows curves of recovery time in microseconds vs. life in hours.

Fig. 4 is a longitudinal section along the 4-4 of Figure 1.

In the figures the envelope, which may comprise for example, a wave guide tube I of rectang-ular cross section and flat end plates 3, generally of larger cross-section for connection and each having a rectangular window 4 of glass or the like. Extending inside the wave-guide 2 and from the shorter walls 5 are four small rectangular metal plates 6. Hollow metal, conical meta1 pieces I extend toward each other from the opposite longer dimension walls between two of the metal plates 6 in a plane transverse to the axis of the wave-guide. The plates 6 and cones I, together with their metallic connections, form a resonant circuit or resonator. The plates 6 extend into the wave-guide I through slots, the ends of the plates being visible from the outside of the guide. The plates 6 are soldered or welded to the guide I to form an hermetical seal.

such resonator or may have some other suitable The so-called broad band, tubes generally have two of them, in addition.

10 Claims. (Cl. 31539) Some trans-receive tubes may have only one.

form of resonator.

to which each of the metal plates 3, with its window 4 also forms a resonator, so that in a tube such as shown in Figure l, with a windowin'feach I end, there are 'four resonant circuits.- Window a broader band of wave-lengths, in the'manner' perature over a considerable range.

well-known in the art. The resonators are generally spaced one quarter wave-length apart. A

keep-alive electrode 9 extends into, but is spaced from one of the cones 1, generally at the resonalation I3 extending through one of the walls and sealed hermetically at its outer end. Thetube is filled with gas which generally includes a quenching gas, such as a water vapor to speed up deionization. The tube may be filled for example with 5 mm. of argon and 3 /2 mm. of water vapor; this pressure is not critical and expressed in the usual manner in millimeters of mercury pressure.

The materials used in the tube should be chosen from as carbon free material as possible and the metal parts should be treated, for example by firing in wet hydrogen to insure this. The firing may be done at 1100 C. in humidified hydrogen, for example. The firing time increases as the temperature is lowered and vice versa, and appears to vary roughly as the square of the tem- The tem- .perature should not be below about 800? 0., however, as at lower temperatures the carbon in the interior of the metal parts of the tube will not diffuse outward to the surface to permit removal.

During the discharge, the residual carbon seems to unite slowly with the oxygen of the water to form carbon dioxide or the like, but the sodium hydroxide then reacts with the latter to form sodium carbonate and water, the water being released to return to the water vapor supply in the tube. This reaction is probably as follows:

My invention has made it possible for the first time to operate a radar transmit-receiver tube at 200 kilowatts for 500 hrs. without serious rise in recovery time. The same tube without the sodium hydroxide or similar material, would last torasshown.

When carbon or carbon containing matter is present in such a tube, the water vapor is apparently decomposed, its oxygen uniting with the carbon to form carbon dioxide or monoxide. When sodium hydroxide is present, the carbon dioxide for example, will react with it to form sodium carbonate and in addition will release water, keeping a supply of .the latter available in the tube. Other compounds which react similar1y,for example an alkaline metal hydroxide or an alkaline earth. metal hydroxide, including potassium hydroxide and lithium hydroxide, may be used.

. What I claim is:

1. An electric discharge tube containinga quenching gas which tends to be removed by reaction with impurities in the tube, and a chemical compound which combines with the product of said reaction to release the quenching gas therefrom.

2. An electric discharge tube containing water vapor and a material which reacts with oxides of carbon to release water vapor.

3. An electric discharge tube containing water vapor and a quantity of sodium hydroxide.

' 4. An electric discharge tube containing water vapor and a quantity of hydroxide of an alkaline metal therein.

5. A transmit-receive tube comprisin a sealed envelope, a resonator therein, water vapor therein at low pressure, and a quantity of hydroxide 4 of an alkaline metal therein.

6. A transmit-receive tube comprising a sealed metal envelope. a resonator, a keep-alive electrode near said resonator, water vapor in said envelope, and a quantity of a hydroxide of an alkaline earth metal therein.

7. A transmit receive tube comprising a sealed envelope, a resonator therein, and water vapor therein at low pressure, said tube being substantially free from the oxides of carbon.

8. An electric discharge tube, including an envelope having a metal wave guide portion and embodying a sealed window, a mixture of a rare gas and water, vapor contained in said envelope, and a quantity of an alkaline metal hydroxide therein.

9; An electric discharge tube of the transmit receive type, including an envelope havinga window portion and a pair of metal parts having opposed portions of limited cross-section and containing a mixture of a rare gas and water vapor. and a quantity of an alkaline metal hydroxide therein.

10. An electric discharge tube containing a mixture of a rare gas and water vapor and being internally substantially free of carbon, said tube also containing a quantity of a hydroxide of the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide.

EZIO THOMAS CASELLINI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

